Stanley Fischer, the vice chairman of the Federal Reserve, announced Wednesday he will retire next month, creating a third vacancy for President Donald Trump to fill at the U.S. central bank.

In a letter to Trump, Fischer, 73, said he was resigning for personal reasons effective on or around Oct. 13, many months before the June, 2018, expiry of his term as vice chair.

In the letter, Fischer said jobs growth had returned to the United States and that "steps to make the financial system stronger and more resilient" had been taken -- actions that may now be weakened by the Trump administration.

His departure leaves the seven-person board of governors with as few as three sitting members, depending on whether and when the Senate confirms Trump nominee Randal Quarles to the role of vice chair for supervision, a job distinct from Fischer's vice chairmanship.

The Senate Banking Committee is scheduled to vote on the nomination on Thursday.

Though the Fed often operates with fewer than its full complement of seven governors, it has never dipped as low as three. Fischer's earlier than expected departure intensifies the urgency for Trump to decide how deeply he wants to overhaul U.S. monetary policy.

Fischer has been a member of the board since May 2014. He previously served as governor of the Bank of Israel from 2005 through 2013. His term as Vice Chairman expires next June.

His resignation will provide President Donald Trump with another opportunity to reshape the Fed. Trump has nominated Randal Quarles for one of the vacancies as vice chairman for bank supervision.

Congress already faces a crowded agenda this fall: It needs to raise the country's borrowing limit, reach a budget agreement to keep the government operating, and plans to take up complicated tax reform.

"It would be easier to keep her around," Swonk said. "You're talking about a lot of turnover when uncertainty about Fed policy is already high."

Trump criticized Yellen's low-interest rate policies during the campaign but has tempered his comments since the election.

Last month in an interview, Trump said he was considering either re-nominating Yellen for a second term as Fed chair or replacing her. One potential candidate was Gary Cohn, a former top executive at Goldman Sachs, who now lead's Trump's National Economic Council.

In the interview with the Wall Street Journal, Trump said he had a "lot of respect" for Yellen and would consider asking her to serve another term. But he also said he was still considering other candidates.

Yellen has said she intends to serve out her current term but has declined to say whether she would consider serving another term.

Reports earlier this year suggested that a leading candidate for one of the other vacant slots is Marvin Goodfriend, an economics professor at Carnegie Mellon University in Pittsburgh.

Another potential nominee for a board seat is Robert G. Jones, the chairman and chief executive of Old National Bancorp. The bank is headquartered in Indiana, Vice President Mike Pence's home state.